The invention generally relates to reconfiguring wireless network capacity and, more particularly, to a method for dynamically reconfiguring wireless network capacity based on current demand and network capacity and will be described with particular reference thereto. However, it is to be appreciated that the invention is also amenable to other applications.
In a wireless network, typically, an equipment provider owns certain centralized network equipment (e.g., a mobile switching center (MSC)) and a wireless service provider provides subscribers with wireless service. In order to provide quality service to its subscribers, the wireless service provider purchases a certain level of network capacity from an equipment provider. Generally, network capacity agreements are handled through the equipment provider's customer service operation using verbal or written communications. Typically, the current network capacity identified in an agreement continues in effect until a new superceding agreement is established. This arrangement is not conducive to day-to-day or hour-to-hour fluctuations in demand for capacity. In many cases, when a wireless network is running at or near purchased capacity overload, some percentage of new incoming calls will be throttled. For example, several U.S. patents assigned to Lucent Technologies and disclosing several methods of overload control are provided below.
U.S. Pat. No. 6,226,277 to Chuah discloses a method for controlling admission of remote hosts to a base station in a wireless communications network based on usage priority. There are at least two user priority classes disclosed and the base station admits a threshold number of remote hosts of the lower priority class and a maximum total number of remote hosts. When a base station receives a connection request from a new user of the higher priority class, if the current total number of admitted users is less than the maximum allowable, the new user of class is admitted, otherwise, the base station checks to see if any lower priority class users are currently admitted and allow disconnection. If so, the base station disconnects the lower priority user and admits the new user. In one embodiment, the base station disconnects the “least recently used” admitted lower priority user that allows disconnection. If it is appropriate to disconnect lower priority users after they are admitted, then lower priority users are admitted as long as the total number of associated users is less than the maximum allowable admitted users. If it is inappropriate to disconnect lower priority users after they are admitted, then lower priority users are admitted only if the number of admitted users is less than the maximum number of total admitted users and the number of lower priority admitted users is less than the maximum allowable admitted number. This approach can be extended to multiple priority classes. In an alternate embodiment, lower priority class users are admitted if the total number of currently associated users of all classes is less than a second threshold, normally lower than the threshold for higher priority users, rather than being based partially (as a second threshold) on the number of currently associated users of that lower priority class.
U.S. Pat. No. 6,469,991 to Chuah discloses a method for overload control in a wireless communications network employing On-Demand Multiple Access Fair Queuing. If the downlink/uplink buffer occupancy of the network has exceeded a high threshold, the base station determines if this is caused by a specific remote host or by a group of remote hosts. If caused by a specific remote host, the base station normally sends a flow control signal to the remote host to prevent it from sending more data, but may alternatively elect to disconnect other remotes if the remote experiencing bad performance is of a higher priority. The base station may additionally reduce the bandwidth shares allocated to any remote that have indicated tolerance for a variable allocated bandwidth. If the measured frame error rates for many remote hosts are increasing, then the base station may elect to disconnect those remote hosts that permit service interruption in order that more bandwidth may be allocated to the remaining users. If a majority of all associated remote hosts experience high uplink frame error rates, the base station may instead send a signal to a wireless hub which can coordinate the actions of other access points. Short packets queued up for so long at the base station that they exceed the time-to-live value allocated will be thrown away. The base station may also or alternatively elect to disconnect some users of a lower priority or redirect them to other nearby base stations that have a lower load. In a particular embodiment, an uplink Frame Error Rate (FER), an average uplink bit rate, a burstiness factor of uplink traffic, and a packet loss rate are measured at the base station for each remote host. Similarly, a downlink Frame Error Rate is measured at each remote host and then each FER is sent to the base station. If an overload condition exits, connections with a Frame Error Rate that has exceeded a threshold for a specified time and that have indicated that their connections can be interrupted are disconnected. Other combinations of the possible actions are suitable, with the exact combination being determined by the base station depending on the particular congestion conditions observed in the network.
U.S. Pat. No. 6,567,416 to Chuah discloses a method for access control in a wireless network having a base station and a plurality of remote hosts. The method includes the optional abilities of making dynamic adjustments of the uplink/downlink transmission ratio, making dynamic adjustments of the total number of reservation minislots, and assigning access priorities by message content type within a single user message stream. The method further provides for remote wireless host paging and for delayed release of active channels by certain high priority users in order to provide low latency of real-time packets by avoiding the use of repeated channel setup signaling messages. In one embodiment, there are N minislots available for contention in the next uplink frame organized into a plurality of access priority classes. The base station allows m access priority classes. Each remote host of access priority class i randomly picks one contention minislot and transmits an access request, the contention minislot picked being in a range from 1 to Ni where N(i+1)<Ni and N1=N. In an alternate embodiment of a method for access control, each remote host of access priority class i and with a stack level that equals 0, then transmits an access request with a probability Pi where P(i+1)<Pi and P1 =1.
U.S. Pat. No. 6,577,871 to Budka et al. discloses a wireless communications service where the service area is divided into multiple cells. A common workstation (COWS) is connected to multiple cell workstations (CEWSs) in hierarchial relation to realize the service. The COWS performs call processing and other tasks common to all cells served by the CEWSs. The latter perform call setups, paging message distributions, and other cell specific operations. First and second central processing unit (CPU) overload control routines are run on the COWS and each CEWS, respectively, to manage their CPU loads. Specifically, different defense actions may be applied by the first and second routines to alleviate the CPU loads of the COWS and CEWS, respectively. These defense actions include COWS's dropping a fraction of paging messages to be processed thereby, and CEWS's dropping a fraction of paging messages, short message service (SMS) broadcast messages and radio frequency (RF) signal strength messages to be processed thereby. In addition, depending on the CPU loads of the COWS and the respective CEWSs, selected classes of mobile units are temporarily denied the wireless communications service.
As can be appreciated from the foregoing, certain approaches to overload control may result in lost revenue to service providers due to dropping of low priority calls. However, service providers may choose to absorb the lost revenue because the duration of the increased demand or capacity overload is typically not long and the cost of purchasing higher capacity from an equipment provider exceeds the lost revenue over the long term. Moreover, changes in network capacity are typically implemented through an equipment/software provider's customer service organization. It may take two or three days before a capacity level changed through customer service actually becomes effective and then it usually remains effective until a subsequent change is processed.
Thus, there is motivation for a method of dynamically reconfiguring wireless network capacity based on current demand and overall capacity.